Once your chair is properly adjusted for your height, check if you can sit at the workstation comfortably with your legs underneath.

If you cannot fit your legs under the workstation or there is not enough space to move them freely, your workstation is too low for you and you should not use such a workstation on a regular basis!
If you can sit comfortably but need to elevate your arms in order to place them over the work surface, your workstation is too high. Adjust the chair height so your elbows are about the same height as the work surface. Use a footrest if you cannot place your feet flat on the floor.
The footrest should be adjustable and support both feet. Keep feet flat and firm on the footrest.